This is certainly muscle memory at work. American Rhythm is unfortunately also a popular social dance and you will have to start out by not doing this at the local social.
Many folks think that they can separate social dance from their competition dancing, but remember, an hour of bad social dancing is the same to your muscles as an hour of quality practice with an amateur partner, so try to not suffer through it with the local senoirs at the tea dance... all you're doing is reinforcing a bad habit.
If you are a follower, you will begin to understand the rhythm during your syllabus work - if a leader, the same, but you must spend time counting. try putting some music in your car as you drive.